DE3539347A1 - METHOD AND DEVICE FOR IMPLEMENTING GAS-SULFURED COMPOUNDS CONTAINED IN SMOKE GASES, LIKE SULFUR DIOXIDE, IN SOLID COMPOUNDS TO BE SEPARATED FROM THE SMOKE GASES - Google Patents

Description

. . DlPL-ING. WILHELM LEGAL LAW MSc

DIPL-PHYS. DR. DIETER GRIESSBACH, DIPL-PHYS. WALTER HAECKER ι DIPL ₁ -PHYS-DR ₁ ULRICHBoHME

PATENT LAWYERS
UHUNDSTR. 14c - 7000 STUTTGART 1

Method and device for converting contained in flue gases gaseous sulfur compounds, such as sulfur dioxide, in solid compounds to be separated from the flue gases

This invention relates to a method of converting to flue gases contained gaseous sulfur compounds, in particular sulfur dioxide, in solid compounds to be separated from the flue gases. The invention also relates to a device for carrying out the aforementioned method.

When burning fuels containing sulfur, such as coal or oil, in steam boiler systems, sulfur compounds that are harmful to the environment are formed, especially sulfur dioxide. Lately attempts have been made in increasing cash registers to develop flue gas cleaning processes, in which the SOp is bound to calcium compounds.

In the known solutions, lime in an aqueous slurry either in carbonate or in hydroxide form is sprayed into the reactor downstream of the boiler. The former form is called the wet limestone process, the latter form the semi-dry process. In its typical form, the reactor is a relatively large container into which the aqueous lime slurry is sprayed from above in a downward direction. The hydraulic diameter of the reactor is larger than the diameter of the flue gas duct, so that the flow velocity of the flue gases decreases when they enter the reactor. The ratio of the height / length of the reactor and the hydraulic diameter (^ / ^ vdr ^ ^ ^s ^ ^ - ^β ^ ^η * it is typically in the order of magnitude of 2 to 5 in the known solutions the radiation turbulence balances the situation so that all reaction stages take place under similar conditions.

A disadvantage of the aforementioned solution is the fact that it has devices for producing and treating the slurry are required, which increases the investment costs considerably.

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In addition, the introduction of the slurry into the reactor is on very failure-prone process, which is synonymous with production losses and disorders. The regulation of the spraying of the slurry requires a high degree of accuracy, because droplets that are too large collect as such on the bottom of the reactor. The consistency of the aqueous calcium hydroxide slurry tries to keep it so high that the smoke in the gas contained '. ".' is sufficient that introduced into the reactor To evaporate water, so dr.cs the atisorption product in the form of a dry powder. However, with such a thick slurry, the nozzles are very prone to clogging and it is difficult to remove the To regulate the droplet size when spraying.

The present invention has for its object to provide a method and apparatus for converting in flue gases contained sulfur compounds, in particular sulfur dioxide, to be separated in the flue gases solid compounds, which are then ^r a simple and economical V can be else separated from the flue gases of the boiler plant, au create.

The main features of the invention are apparent from the appended Claims.

In contrast to the aforementioned already known solution, one leaves the velocity of the gaseous sulfur compounds containing Flue gases in the reactor do not decrease significantly, but instead the flue gases are channeled through an elongated reaction zone in which the velocity of the flue gases remains essentially unchanged, the residence time of the reaction over the length of the reaction zone is regulated and the progress of the reaction by introducing one or more powdery reagents at one or several points of the reactor zone length can be regulated in the flue gas stream.

In contrast to the previously known solution, this will be Reagent that reacts with the gaseous sulfur compounds of the flue gases is not introduced into the reaction zone as an aqueous slurry, Instead, the water is fed into the reaction zone separately from the reagent in the form of a lever or steam, while the reagent is being fed is brought into the reaction zone in powder form. In this way

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ve im ei α et nan those with the production, the handling and the nozzle associated with the aqueous slurry in the reactor Difficulty .. The separate introduction of water and / or steam on the one hand and powdered reagent on the other hand into the reactor can be done easily and cheaply from a technical point of view. Also design maintenance and servicing of such "devices is easy, and the operation of the system does not require extensive staff,

Those led to one end of the elongated reaction zone Flue gases can already be powdered alkali and / or alkaline earth metal oxide and / or hydroxide in dust form or water in I mist form and / or contained as water vapor, v / whether ei then correspondingly water and / or water vapor or powdery alkali and / or alkaline earth metal oxide and / or hydroxide on one or more consecutively v / earth located places in the reactor. As an alternative or in addition to this, of course, powdery products can also be used Oxide and / or hydroxide as well as water and / or water vapor are separated from one another, possibly at the same point, but separately from one another, are brought into the reactor itself. Instead of mere V / asters can also contain weakly concentrated calcium or magnesium hydroxide emulsions sprayed v / earth.

In a certain conveniently located case, powdery oxide and / or hydroxide is introduced into the reaction zone at at least two consecutive points, with the feeding of water and / or water vapor in the reaction zone between these entry points lying one behind the other or at the same location as the powdery one Reagent can be done.

Raise the aforementioned reagents and water can convert the sulfite formed during the reaction into sulfate or oxygen or oxygen-containing gas, preferably in preheated form, are introduced into the end section of the reaction zone. At the same time, hot flue gases can be used in the reaction zone end section to heat the gases in the reactor end section before the Ground dust separation initiated.

The temperature of the reaction zone to be introduced into the flue gases is 50-80O ⁰ C, but preferably 9O-2OO ° O.

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The powdery reagent to be introduced into the reaction zone is preferably calcium oxide and / or hydroxide that is fed into the boiler system fed in calcium carbonate can come, which breaks down to Ealziumoxid there and which becomes water in the boiler system ΐιηά / or water vapor entered, continue to form calcium hydroxide can. The carbonate can either be dry in the boiler system Powder or, in certain cases, also introduced as an aqueous slurry.

In a departure from the already known solution mentioned above, it works one in the device according to the present invention with an elongated reactor, for example with a tubular reactor, whose The ratio of length and hydraulic diameter is large, namely typically about 10 or even more. In this In the reactor, the speed of the flue gases does not decrease significantly, but remains high that those involved in the reaction gaseous and solid substances are entrained by the flue gases and transported onwards. The required residence time can be adjusted over the length of the reactor, and behind the reactor the dust-like or mist-like substances can either be in be separated from the flue gases in a separate separator or in the conventional dust separator of the boiler system. Under hydraulic In this context, diameter is to be understood as the cross-sectional area of the reactor.

Such an elongated reactor also offers the advantage that different conditions exist in the individual reactor sections set or that even different reactor ratios can be set in the individual sections. the For example, the temperature can vary depending on whether the reaction is heat is released or heat is bound when water evaporates. That way, the process can be done in the way you want Optimize the way.

The elongated reactor can be used in the sulfur-containing fuels incinerating boiler system can be firmly integrated, for example in the way that the reactor is in the boiler house or outside of it arranged between the boiler heating surfaces and the dust collector is. The reactor can, however, also be arranged completely separately from the boiler system behind the dust separator, whereby

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then the oxide is entered separately in the smoke channel instead of in the boiler v.ira, and then a separate dust collector is required is. This procedure offers the advantage that the fly ash and the resulting sulphate-V-sulphite mixture are removed from the flue gas flow separate v / earth.

In the following the invention with reference to the attached Drawings will be described in detail; 1 shows the schematic sectional view of a preferred embodiment of the invention;

Fig. 2 shows the schematic sectional view of another embodiment of the invention.

In the drawing, the reference number 1 denotes the furnace of the boiler system, in which sulfur-containing fuel 17 usually " is burned with the supply of air IS. The ones containing sulfur dioxide Flue gases 15 cool in the boiler on the heating surfaces 2 and in the preheater 3 of the combustion air 18. Be behind the boiler 1 the flue gases 16 according to the invention passed into the elongated reactor 4, to which the dust separation system 5 "and the chimney 6 connect.

The reagent intended to bind the sulfur, preferably calcium carbonate, is from the storage container 7 via the dosing feeder 8 brought into the air flow of the blower 9 of the pneumatic conveyor system and either reaches the line 10 into the Upper part of the boiler 1 and / or via the line 11 in the front Section of the reactor 4 and possibly via line 12 to another point further back in the reactor 4. Ausseraem is in the elongated reactor 4 either only at its front end or at several distributed over the length of the reactor Place 15 water injected through the nozzles. Furthermore, at an appropriate point of the reactor 4 in this via the Line 14 hot air or via line 13 flue gas can be entered around the temperature of the flue gases in the end section of the reactor to increase before reaching the dust collector 5.

The reagent is preferably used in an excess amount used on the sulfur contained in the fuel 17. The reagent can either be fed directly into vessel 1 via line 10

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1 and / or at one or more points 11, 12 of the reactor 4 directly introduced into this. Over the line 12 are preferably entered not more than 50 -j of the total amount of reagent.

The amount of water entered by the pump 19 via the nozzles 15 is preferably dimensioned at most so large that it evaporates as completely as possible under the action of the heat of the flue gases 16. If necessary, however, the flue gas temperature in reactor 4 can be determined Supply of hot flue gases 16 via the bypass line 13 in the end portion of the reactor 4 is raised v / ground.

In Pig. 2, the reference numerals designate the corresponding objects as in Pig. 1. The solution shown in Fig. 2 differs from the one in Pig. 1 is that the reactor is now only behind the flue gas separator, usually behind the electrostatic precipitator 20, is arranged. You then get the plug ash on the one hand and the potassium compounds obtained as a result of the reaction on the other hand, essentially completely separated from one another, since the plug ash is deposited in front of the reactor and the reagent, preferably ilium oxide, only after the plug ash has been deposited is introduced into the reactor. The reactor is of course followed by its own pesticide separator, for example a conventional one Electrostatic precipitator or another suitable separating device.

Instead of calcium carbonate or oxide, any other oxide can be put into boiler 1 or reactor 4, or a Z'x 0: -: id decomposed alkali and / or alkaline earth metal carbonate, such as potassium I-magnesium carbonate, be introduced. Although the process and the reactor work well with a single reagent, for example carbonate or oxide, the system can also be operated with several different reagents at the same time in order to use reagents that are available cheaply will. The reagents can either be mixed with one another at the same time. Entry point or the same entry points or one at separate entry part cn introduced as required. The calcium carbonate flowed from calcium carbonate, or from calcium magnesium carbonate, which, when placed in the kettle, had decomposed into oxide and carbon dioxide.

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In the following v.ärd the invention on the basis of Bsiopielen in detail

described.

TJnt3i "3 would require a reactor with a cross-sectional area of approximately (0.4 χ C, 4) m ~ and a length of about 20 m. Into the reactor ■ flue gases were blown in at different temperatures, the contained mainly calcium oxide-containing dust and approx. 900 ppm SCp. In addition, water was sprayed into the reactor.

Form the calcium oxide contained in the smoke gases and the water Calcium hydroxide, which reacts as a highly reactive substance with the oxides of sulfur.

(l) GaO + H ₉ O - Ga (OH) ₀ "+ SO,

Ga (OH) ~> GaSO

₃ + H ₂ C

The reactor ratios and the reaction results (analysis) go from Table 1, the first column of which is the amount of calcium oxide, defined as the calcium-Mo! ratio in relation to sulfur, whose zv: the first column shows the temperature of the flue gas introduced into the reactor, the third column shows the temperature of the flue gas its exit from the reactor, its fourth column the Schv / efeldioxidreduktion in percent, the fifth column of which is the percentage of fly ash in the solid matter, the sixth column of which is the percentage Sulphite and sulphate content in the solid and the seventh column of which contains the content of the other compounds in the solid.

Table 1 T. Φ
¹ OIIt S0 _o reduct. Composition L. CaSO., / d. Product Ca / S m flight CaSO ^ Other ver 65 ⁰ G ash 23 ^c / o ties 50 ⁰ C 68 56 % 76 % 26th 1> o 0.52 90 72 82 61 24 13th 1.56 200 62 87 51 26th 25th 2.20 120 68 96 53 25th 21 2.22 110 63 93 53 20th 22nd 2 ^ 120 110 98 43 15th 37 4.0 800 72 38 47 4.1

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Example 2

Flue gases are introduced into the reactor as in Example 1, their Plug ash has been separated separately with an electrostatic precipitator. The calcium oxide is added to the flue gases after the electrostatic precipitator in front of the reactor.

The test results associated with the implementation are compiled in Table 2: The amount of calcium oxide is the calcium molar ratio specified for sulfur; the percentages of calcium sulphite, calcium sulphate and the combined remaining Compounds on the solid formed in the reaction are each given in a separate column. The flue gas inlet and -austrittstemperatiiren sov.de the sulfur dioxide reduction in percent are given in a corresponding manner as in Table 1.

Table 2

^Ca / ^{3-in T} out

1.56 9O ⁰ C 63 ⁰ C
2.22 120 68

4.0 120 63

Example 3

Calcium oxide is as in Example 2 behind the electrostatic precipitator in the Reactor introduced, but an oxidizing agent or oxygen-containing gas, such as air, is now added to the flue gases behind the reactor, v / whether ei the calcium sulfite to sulfate o: -: ydiert. The reaction conditions and results are shown in Table 3, respectively Manner as indicated in Table 1 and Table 2.

S0 ₂ reduct. CaSC ₇ Iro duct analysis e Other connection 32 # 44 i CaSO, 35; p 93 36 21 · ί 47 93 23 · 17th 61 11th

Table 3 m
"out SC ₂ reduct. CaSC CaSC , Other conn
fertilize Ca / ST _in 63 ⁰ C 32> p J-, H- / O 65 X 33 Si 1.55 9O ⁰ C 63 93 0.3 53 46 2.22 120

4, C 120 63 93 0.3 35 64

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Claims (13)

Claims 1. Process for converting gaseous sulfur compounds contained in flue gases into solid compounds to be separated from the flue gases, characterized in that the gaseous Sch wef el compounds containing flue gases (16) at one end an elongated reaction zone (4) are passed into this, and that in the reaction zone also separately a) powdery alkali and / or alkaline earth metal oxide (7) and / or hydroxide and b) water (15) and / or water vapor introduced at one or more points and that flue gas suspension containing solid sulfur compounds is discharged at the opposite end of the reaction zone will. 2. The method according to claim 1, characterized in that that at said one end of the elongated reaction zone (4) in this together with the flue gases powdery oxide and / or Hydroxide (16) and separately therefrom in the initial section of the reaction zone water (15) and / or water vapor is introduced. 3. The method according to claim 1 or 2, characterized in that powdery oxide and / or hydroxide on at least two successively arranged points (11, 12) is introduced into the reaction zone, and that water (15) and / or water vapor between these entry parts located one behind the other into the reaction zone is introduced. 4. The method according to any one of the above claims, characterized in that in the end section of the reaction zone (4) Oxygen or oxygen-containing gas (14), preferably in a preheated (3) state, is introduced. 5. The method according to any one of the above claims, characterized in characterized in that hot flue gases (I3) are introduced into the end section of the reaction zone (4). 6. The method according to any one of the claims, characterized in that at said one end of the reaction scene (4) are introduced into these flue gases (16), the temperature of which is 50 to 80O ⁰ C, preferably SO to 200 ⁰ C. BATH ORIGINAL «Β ·« I fet * »* ♦« · 7. The method according to any of the above claims / characterized characterized / that in the reaction zone (4) powdered calcium oxide (7) and / or hydroxide is introduced. 8. The method according to any one of the above claims / characterized / that in the reaction zone (4) powdered potassium magnesium hydroxide is introduced. 9. Device for preparing gaseous sulfur compounds contained in flue gases / in particular sulfur dioxide / in by the Solid connections to be separated / marked through an elongated reactor (4), at one end of which there is an inlet opening for the gaseous sulfur compounds containing smoke gases (16) and its opposite End of an outlet opening for the solid sulfur compounds containing Flue gas suspension is present / and which also has organs (15) for introducing water and / or steam and organs (10 / 11,12) for separate entry of powdery alkali and / or Alkaline earth metal oxide (7) and / or hydroxide in the reactor (4) at one or more points distributed over the length of the reactor having. 10. The device according to claim 9, characterized in that that the reactor (4) the boiler (1) in which sulfur-containing fuels (17) are fired, is firmly affiliated. 11. The device according to claim 9 or 10, characterized in that the reactor downstream of the solids separator Boiler flue gases is arranged. 12. The device according to claim 10 or 11, characterized / that the device (10) for introducing the powdery material into the reactor is in communication with the furnace (1) / around the powdery material together with the flue gases (16) to pass the furnace (1) into the reactor. 13. Device according to any one of the above claims, characterized in characterized in that the ratio of the length of the elongated reactor (4) and its hydraulic. Larger diameter than 10 is. BATH ORIGINAL